simplify nogil declarations in std*.pxd

Cython/Includes/stdio.pxd

-cdef extern from "stdio.h":
+cdef extern from "stdio.h" nogil:
     ctypedef struct FILE
-    int printf(char *format, ...) nogil
-    int fprintf(FILE *stream, char *format, ...) nogil
-    int sprintf(char *str, char *format, ...) nogil
-    FILE *fopen(char *path, char *mode) nogil
-    int fclose(FILE *strea) nogil
+    int printf(char *format, ...)
+    int fprintf(FILE *stream, char *format, ...)
+    int sprintf(char *str, char *format, ...)
+    FILE *fopen(char *path, char *mode)
+    int fclose(FILE *strea)
     cdef FILE *stdout
-    int scanf(char *format, ...) nogil
+    int scanf(char *format, ...)

Cython/Includes/stdlib.pxd

 
-cdef extern from "stdlib.h":
-    void free(void *ptr) nogil
-    void *malloc(size_t size) nogil
-    void *realloc(void *ptr, size_t size) nogil
-    size_t strlen(char *s) nogil
-    char *strcpy(char *dest, char *src) nogil
+cdef extern from "stdlib.h" nogil:
+    void free(void *ptr)
+    void *malloc(size_t size)
+    void *realloc(void *ptr, size_t size)
+    size_t strlen(char *s)
+    char *strcpy(char *dest, char *src)